US6685466B2 - Rotary hearth furnace for producing reduced metal and method of producing reduced metal - Google Patents

Rotary hearth furnace for producing reduced metal and method of producing reduced metal Download PDF

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US6685466B2
US6685466B2 US09/988,521 US98852101A US6685466B2 US 6685466 B2 US6685466 B2 US 6685466B2 US 98852101 A US98852101 A US 98852101A US 6685466 B2 US6685466 B2 US 6685466B2
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hearth
furnace
side wall
lateral
producing reduced
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US20020123019A1 (en
Inventor
Takao Harada
Hidetoshi Tanaka
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Kobe Steel Ltd
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Kobe Steel Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B9/32—Casings
    • F27B9/34—Arrangements of linings
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C21B13/105—Rotary hearth-type furnaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/16—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a circular or arcuate path
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B9/36—Arrangements of heating devices
    • F27B2009/3607—Heaters located above the track of the charge
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0043—Floors, hearths
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/04—Casings; Linings; Walls; Roofs characterised by the form, e.g. shape of the bricks or blocks used
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/12—Casings; Linings; Walls; Roofs incorporating cooling arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0073—Seals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
    • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen

Definitions

  • the present invention relates to a rotary hearth furnace for producing reduced metal through heating and reducing carbon containing materials composed of at least metal oxide-containing material and carbonaceous reduction material, and in particular, to a structure of a hearth.
  • Such a reduction method can be used not only for production of metallic iron but also for reduction of nonferrous metal such as Ni and Cr.
  • Reduced iron is produced by the rotary hearth furnace as an example as follows (refer to FIG. 5 ).
  • Powdered iron oxide and powdered carbonaceous material are mixed and pelletized to form green pellets.
  • pellets are heated up to such a temperature area that combustible volatile components generated from the pellets may not ignite to remove contained moisture to obtain dry pellets (hereinafter will be simply referred to as pellet).
  • the pellets 7 are supplied into the rotary hearth furnace 17 by using a suitable charging unit 13 to form a pellet layer on the rotary hearth 1 .
  • the pellet formed a layer is radiant heated for reduction by combustion of a burner 17 c installed in the upper part of the furnace inside to produce reduced iron through metalizing.
  • Such reduced iron is cooled to a temperature allowing mechanical handling by direct gas spraying to reduced iron by a cooler 18 or indirect cooling by using cooling water jacket, and then discharged from the furnace by a discharging unit 12 to obtain reduced iron products.
  • FIG. 6 is a sectional view of the rotary hearth furnace for illustrating the said process ( 4 ).
  • the rotary hearth 1 has a number of wheels 19 attached to the bottom thereof so as to be rotated at a constant speed on a circular track 20 by a driving unit (not shown).
  • a hood 21 for covering the upper part of the rotary hearth consists of a ceiling 22 and side wall 2 and fixed to the ground. Therefore, it is necessary to shield gas within the furnace and the atmospheric air while allowing the rotary hearth 1 to be rotated freely about the hood 21 , and water-sealing means 4 is installed in general between the rotary hearth 1 and the side wall 2 .
  • the water sealing means 4 as shown in FIG.
  • the hearth 1 Since the hearth 1 is radiant heated up to a high temperature from the upper part by the burner 17 c installed in the hood 22 when the pellets 7 are loaded on the upper part thereof, a structure is adopted in which an insulating unshaped refractory 5 is layered at the lower surface side of the hearth and a heat-resisting unshaped refractory is layered at the upper surface side of the hearth.
  • the pellets 7 are not loaded near the tips of the hearth lateral ends 1 a . Therefore, while the refractory upper surface 1 u of the hearth lateral ends 1 a is directly exposed to radiant heat from the furnace inside such as the hot burner 17 c , the inside of the ceiling 22 of the hood 21 and the inside of the side wall 2 and raised in temperature to expand in a large margin, the refractory side walls 1 s of the hearth lateral ends 1 a are not directly exposed to radiant heat and thus do not expand.
  • refractory hearth edge of the hearth lateral ends 1 a which tends to have spalling together with low strength due to insufficient burning.
  • the hearth edge 1 e has spalling, broken pieces fall down to the seal trough 4 and the pellets 7 loaded near the hearth edge 1 e tend to fall down to the seal trough 4 as well.
  • This not only decrease the yield of the reduced iron products but also may stop the rotation of the hearth 1 since a sludge-form deposit occurs at the bottom of the seal trough 4 and the leading end of the skirt 4 a is buried in the deposit.
  • the invention according to claim 1 relates to a rotary hearth furnace for producing reduced metal through heating and reducing carbon containing materials composed of metal oxide-containing material and carbonaceous reduction material, comprising: a hearth for loading said carbon containing materials thereon; and a hood for covering the whole hearth form upside, wherein the upper parts of both lateral ends of said hearth are covered with side wall lower end of the hood; and cooling means is provided at the lower end of the side wall.
  • the upper sides of the both lateral ends of said hearth upper surface may be covered with a portion of the side wall lower end.
  • the side wall lower end of the hood covers over the lateral ends of the hearth upper surface so that the refractory of the lateral ends is not directly exposed to radiant heat from the furnace inside. Then, the hearth edge is not heat distorted and spalling thereof may not take place. Also, the cooling means is installed in the side wall lower end to moderate heat distortion in furnace inside edges of the side wall lower end and to avoid spalling in these portion.
  • the invention according to claim 2 relates to the rotary hearth furnace for producing reduced metal according to claim 1 , a vertical section including a rotary axis of said rotary hearth furnace has a combination of ⁇ and L satisfying both of the following equations 1 and 2: L ⁇ tan ⁇ ⁇ ⁇ ⁇ 30 Equation 1 L ⁇ 0.16 ⁇ ⁇ ⁇ 2 - 2.44 ⁇ ⁇ ⁇ + 92 Equation 2
  • ⁇ (°) is the minimum depression angle for exposing at least a portion of the hearth lateral end when said hearth lateral end is looked downward from the leading end at said hearth center side in the side wall lower end
  • L (mm) is the horizontal length from said leading end to a position on said lateral end to be the minimum depression angle
  • the temperature of the edge can be reduced to such a degree that spalling may not take place in the hearth edge when the atmospheric temperature in the furnace is at or under 1200° C., the effect of the invention according to claim 1 can be ensured.
  • the invention according to claim 3 relates to the rotary hearth furnace for producing reduced metal according to claim 2 , wherein said equation 2 is replaced from L ⁇ 0.16 ⁇ 2 ⁇ 2.44 ⁇ +92 to L ⁇ 0.19 ⁇ 2 ⁇ 2.44 ⁇ +100.
  • the temperature of the hearth edge can be reduced to such a degree that spalling may not take place in the hearth edge when the atmospheric temperature is at or under 1400° C., and thus the effect of the invention according to claim 1 can be ensured.
  • the invention according to claim 4 relates to the rotary hearth furnace for producing reduced metal according to any one of claims 1 to 3 , wherein said lateral end has an inclined surface with upward gradient toward a lateral leading end opposed to the hearth central side.
  • carbon containing materials do not fall down to the water sealing means (seal trough) without interfering rotation of the hearth.
  • the invention according to claim 5 relates to the rotary hearth furnace for producing reduced metal according to any one of claims 1 to 4 , wherein said lateral end is formed of a burned precast refractory or a shaped refractory.
  • the refractory of the lateral end can be burned outside the furnace to have a sufficient degree of strength, by which the problem of low strength of the lateral end due to the insufficient burning described in the above can be prevented so that spalling of the hearth edge can be prevented more effectively.
  • the invention according to claim 6 relates to a method of producing reduced metal through heating and reducing carbon containing materials composed of metal oxide-containing material and carbonaceous reduction material, comprising the steps of: charging said carbon containing materials on said hearth of rotary hearth furnace for producing reduced metal according to any one of claims 1 to 5 ; and hot reducing the carbonaceous heat-treated products.
  • spalling does not take place in the hearth edge and thus the pellet may not fall down to the seal trough so that the yield of reduced metal can be improved.
  • FIG. 1 is a sectional view for illustrating a hearth structure of a rotary hearth furnace for producing reduced metal of the present invention
  • FIG. 2 illustrates the relation among an overlapped length L, a depression angle ⁇ and the temperature of a hearth edge
  • FIG. 3 shows the combination area of the overlapped length L and the depression angle ⁇ of the invention according to claims 2 and 3 ;
  • FIG. 4 is a sectional view for illustrating a hearth structure having an inclined surface with upward gradient toward the hearth edge of the invention according to claim 4 ;
  • FIG. 5 is a plan view for schematically illustrating a rotary hearth furnace for producing reduced iron.
  • FIG. 6 is a sectional view for illustrating an original hearth structure of a rotary hearth furnace for producing reduced iron.
  • FIG. 1 shows an embodiment of the invention.
  • a structure near a side wall of a vertical section in a radial direction of a rotary hearth for example, a section along A—A line shown in FIG. 5
  • a combustion unit shown in FIG. 5 an area from a charging unit 13 to a cooling unit 12 in a rotational direction.
  • both of the outer periphery side and the inner periphery side have the same structure near the side wall, only one of them is shown.
  • the hearth 1 consists of a layered-configuration from the bottom to the top, for example, in the order of an insulating refractory layer 5 a , a heat-resisting refractory layer 5 b and a hearth material layer 6 , except for a lateral end 1 a , which is constituted by providing a layer of a precast refractory which is burned 5 c hereinafter will be referred to as burned precast refractory on the insulating refractory layer 5 a .
  • the lateral end 1 a is adjacent the lower end 2 a of a side wall 2 of a hood and covered thereby to be overlapped at a certain portion.
  • the burned precast refractory 5 c when a frame is prepared, as the burned precast refractory 5 c , with a shape for dividing the outer periphery side and the inner periphery side of the hearth 1 into a suitable number in the circumferential direction and a burned material (curb brick) is prepared by casting an unshaped refractory into the frame followed by forming outside the furnace and burning to be installed in the furnace, even if any one of curb bricks 5 c is, spalled the prearranged curb brick 5 c replaces the spalled one after the furnace is cooled so that the operation can be reopened without delay.
  • a burned material curb brick
  • the lower end 2 a of the side wall is provided for example as an unshaped refractory, in which cooling means 3 is buried for example as a metallic cooling water pipe.
  • the cooling water pipe 3 is welded with an anchor plate 3 a so that a cooling effect can reach up to the refractory surface.
  • a box-shaped cooling water channel for example, may be used instead of the cooling water pipe 3 , and cooling may be carried out using gas instead of water. Since cooling is carried out up to the refractory surface, the strength of the refractory itself can be raised thereby preventing wear of the refractory surface due to the welding and the like.
  • the temperature difference is reduced between the furnace inner surface in the side wall lower end and the lower surface so that heat distortion of the side wall edge 2 e can be moderated to prevent damage of the side wall edge 2 e . If the cooling means 3 is not installed in the side wall lower end 2 a , the side wall edge 2 e is damaged due to the heat distortion by the temperature difference between the furnace inner surface and the lower surface, and an effect covering (A) the hearth lateral end 1 a is restrained so that the hearth edge 1 e may be damaged.
  • the cooling means 3 such as cooling water pipe or box-shaped cooling water channel in the side wall lower end 2 a since the buried cooling means 3 can be adapted to serve to support the weight of the side wall refractory 5 in addition to the said effect.
  • Installation of the hearth refractory is preferably performed, for example, according to the following order: first, the insulating shaped or unshaped refractory layer 5 a is installed across the whole hearth width followed by aging and solidification. Over the refractory layer 5 a , are arranged the curb bricks 5 c of the burned precast refractory across the whole inner and outer peripheries of the hearth lateral end to form a bank 1 a (which indicates A, however description of A will be omitted hereinafter).
  • the heat-resisting unshaped refractory 5 b is installed between the bank 1 a of the inner and outer peripheries as depressed slightly more than the bank 1 a .
  • the furnace is heated by the burner 17 c to dry and burn the unshaped refractory 5 b .
  • a hearth material 6 having iron oxide as the main ingredient as the shape of lump or powder, which is heated by using a burner 17 c to form the hearth surface for loading pellets 7 .
  • This provides the hearth free from damage due to the spalling and capable of maintaining flatness since an accumulated material layer formed on the hearth upper surface may be easily removed.
  • the curb brick 5 c may be installed after the unshaped refractory 5 b is applied, dried and solidified.
  • the inventors found that spalling of the hearth edge 1 e takes place due to the heat distortion of the hearth edge 1 e , which is closely related to the temperature of the hearth edge 1 e , and studied as follows.
  • the temperature near the hearth edge 1 e is changed due to the geometric configuration near the hearth lateral end 1 a , whereas direct measurement thereof is difficult. Therefore, considering radiation heat-transfer via a gap between the hearth 1 and the side wall 2 from the furnace inside and conduction heat-transfer transferred from the upper surface of the hearth 1 , the temperature of the hearth edge and the like are estimated by means of heat-transfer calculation.
  • the depression angle ⁇ and the overlapped length L are varied into three kinds by using the burned precast refractory of alumina-based castable refractories to the hearth lateral end in a existing rotary hearth furnace (hearth diameter 8.5 m and hearth width 1.25 m).
  • the atmospheric temperature is set about 1400° C. in the said furnace to carry out experiments of producing reduced iron for a certain time period (22 to 30 days), spalling of the hearth edge 1 e is observed and results thereof are shown in FIG. 2 .
  • ⁇ marks mean that the hearth edge 1 e has no spalling
  • x marks mean that the hearth edge 1 e has spalling.
  • the hearth edge 1 e has very low probability of spalling when the temperature of the hearth edge is kept at or under 550° C.
  • a overlapped length L is set as large as possible and depression angle ⁇ is set as small as possible in order to keep the temperature of the hearth edge at or under 550° C., however, it is necessary to consider the following conditions.
  • the gap between the hearth lateral end 1 a and the side wall lower end 2 a is set too small, the pellet 7 may be choked in the gap to interrupt rotation of the hearth 1 . Therefore, the gap is preferably at least 30 mm considering that the diameter of the pellet in use is 5 to 20 mm in general.
  • Equation 2 is obtained by reading combinations of the overlapped length L and dip ⁇ when the temperature of the hearth edge is 550° C. from FIG. 2 approximating in curve.
  • FIG. 3 shows the said Equations 1 and 2 .
  • an area over a curve corresponds to Equation 1
  • another area over a curve b corresponds to Equation 2 . Therefore, combinations of L which is arbitrary points in the area over both of the curve a and the curve b (including those points on the curves) and ⁇ so that spalling of the hearth edge 1 e can be prevented.
  • the overlapped length L is set at or under 400 mm, the open area of furnace hearth can be minimized which is not used for production of reduced iron while it is ensured a thickness necessary for heat insulation of the furnace which is the original purpose of the side wall 2 , which is preferable in economical basis such as reduction of furnace manufacturing cost. Therefore, the combinations of L and ⁇ are selected in the range of an inclined region of FIG. 3 defined by the straight line c and the curves a and b, in which a region marked with dotted lines under the straight line c corresponds to a condition of L ⁇ 400 mm. Then, preferably, spalling of the hearth edge 1 e can be prevented and manufacturing cost of the furnace can be reduced.
  • Equation 2 shows a preferred condition that the atmospheric temperature is 1400° C., which is near the upper limit, in the furnace in production of reduced iron by the rotary hearth 17 , whereas the atmospheric temperature in the furnace is sometimes set 1200° C. caused by several limitations such as raw material features in use.
  • the conditions of Equation 2 are moderated since the temperature of hearth edge is lowered compared with the atmospheric temperature in the furnace of 1400° C.
  • the atmospheric temperature is set 1200° C. and heat-transfer is calculated as the same as above to obtain a drawing (not shown) as in FIG. 2, by which the hearth edge 1 e has low probability of spalling.
  • Equation 2′ is obtained as follows:
  • Equation 1 is a restricting condition that is simply geometrically determined regardless of the atmospheric temperature in the furnace with no change, in which a preferred combination area of the overlapped length L and the depression angle ⁇ in the atmospheric temperature in the furnace at 1200° C. satisfies both of Equation 1 and Equation 2′.
  • Equation 2′ is drawn together in FIG. 3
  • an area over the curve b′ corresponds to Equation 2′ and the area over the curve a and the area over the curve b′ (including the area on the curve b′),correspond to the range of selecting L and ⁇ , which is wider than when the atmospheric temperature in the furnace is 1400° C.
  • a suitable furnace structure may be used based upon the technical principle of the invention in this case.
  • the range for preventing spalling of the hearth edge 1 e can be expressed as in FIG. 3 .
  • an inclined surface l k may be formed having upward gradient toward the hearth edge (lateral leading end) 1 e on the furnace lateral end 1 a as shown in FIGS. 4A and 4B.
  • the angle of the inclined surface 1 k is not specifically restricted, in the hearth lateral end in a region (inner periphery side in general) different from the region (outer periphery side in general) where the pellets of reduced iron are discharged from the furnace by a discharging unit, the angle is preferably set at least angle of repose of the pellets 7 for example at least 25° so that the pellets 7 reaching the inclined surface may easily return into the original furnace.
  • near the hearth edge 1 e is previously cut obliquely (FIG. 4C) or given with radius R (not shown) to have a configuration for dispersing stress so that the hearth edge 1 e may hardly have spalling.
  • depression angle ⁇ is the minimum depression angle for exposing at least a portion of the hearth lateral end 1 a when the hearth lateral end 1 a is looked downward from the side wall edge 2 e .
  • the overlapped length L is a horizontal distance up to a position 1 z on the hearth lateral end 1 a having the minimum depression angle ⁇ .
  • the position 1 z is based upon definition of the overlapped length L and the depression angle ⁇ , since radiant heat does not directly reach an area of the furnace beyond the position 1 z while radiant heat directly reach the other area of the furnace inward from the position 1 z , the position 1 z becomes a site for generating heat distortion in the maximum amount.
  • the carbon containing materials are not limited thereto but may include briquette shape, plate shape, nugget shape, powder mixture and the like.
  • a rotary hearth furnace has hearth diameter 8.5 m and hearth width 1.25 m, and modification is variously made about overlapped length L, depression angle ⁇ , existence of inclined surface with upward gradient toward the hearth edge (lateral leading end), burying of the cooling water pipe in the side wall lower end, type of the lateral end refractory and installing method, after the atmospheric temperature in the furnace is set 1400 or 1200° C. and reduced iron is produced for a predetermined time period (about 30 days) under each condition, the degree of damage of the hearth edge and the increase of sludge in the seal trough are investigated. Results thereof are shown in Table 1 as follows.
  • a hearth structure is selected in which the upper part of the conventional hearth lateral end is not covered with side wall lower end, and the hearth lateral end is formed by casting alumina-based castable refractories(containing Al 2 O 3 50 mass% and SiO 2 45 mass%) in the furnace.
  • alumina-based castable refractories containing Al 2 O 3 50 mass% and SiO 2 45 mass%) in the furnace.
  • the hearth lateral end is formed by casting the alumina-based castable refarctories in the furnace as in experiments Nos. 1 and 2, in which the length of covering directly over the lateral end with the side wall lower end (overlapped length) is slightly longer than in experiment No. 2 and the depression angle is also slightly smaller than in experiment No. 2 (L is 200 mm and ⁇ is 17°), and further, in the side wall lower end is buried the cooling water pipe welded with the anchor plate.
  • the hearth edge has only slight cracks which does not reach spalling and no damage is found in the side wall edge.
  • the increase of sludge in the seal trough is reduced in a great amount.
  • the cooling means is installed, spalling of the side wall edge is prevented and the effect of shielding radiant heat from the furnace inside is enabled to prevent spalling of the hearth edge, and as a result, the pellets and the like can be prevented from falling down to the seal trough.
  • the overlapped length L and depression angle ⁇ have the same value as experiment No. 5 and an inclined surface with upward gradient toward the edge is formed at the most edge side of the hearth lateral end (horizontal length is 100 mm and gradient is 30°), in which other conditions are the same as in experiment Nos. 4 and 5.
  • any of the hearth edge and the side wall edge is not damaged at all and the increase of sludge in the seal trough is not found almost at all.
  • the side wall lower end of the hood covers over the lateral ends of the hearth upper surface so that the refractory of the lateral ends is not directly exposed to radiant heat from the furnace inside. Then, the hearth edge is not heat distorted and spalling thereof can be prevented. Also, since the cooling means is installed in the side lower end, heat distortion of the side wall edge can be moderated thereby preventing spalling in these portions.
  • the lateral end has an inclined surface with upward gradient toward a lateral leading end, carbon containing materials do not fall down to the seal trough so that the effect of the invention according to claims 1 to 3 can be obtained without interfering rotation of the hearth.
  • the refractory of the lateral end can be burned outside the furnace to have a sufficient degree of strength, by which the problem of low strength of the lateral end due to the insufficient burnig can be prevented so that spalling of the hearth edge can be prevented in a more effective manner.

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  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
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JP2000372876A JP3553873B2 (ja) 2000-12-07 2000-12-07 還元金属製造用回転式炉床炉及び還元金属の製造方法

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040163493A1 (en) * 2003-02-26 2004-08-26 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Method for manufacturing reduced metal
US20050087039A1 (en) * 2001-11-12 2005-04-28 Shoichi Kikuchi Method of producing metallic iron
US20050211020A1 (en) * 2002-10-18 2005-09-29 Hiroshi Sugitatsu Ferronickel and process for producing raw material for ferronickel smelting
US20090136887A1 (en) * 2005-10-11 2009-05-28 Kab. Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Rotary hearth furnace

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR803478A (fr) 1936-03-14 1936-10-01 Stewarts & Lloyds Ltd Perfectionnement aux fours à sole tournante
DE1151823B (de) 1960-05-16 1963-07-25 Mannesmann Ag Drehherdofen zum Waermen von Stahlbloecken
US4227875A (en) * 1978-09-12 1980-10-14 Calcimatic International Limited Rotary hearth for calcining kiln
CH649096A5 (en) 1981-11-11 1985-04-30 Technomet Ag Process and equipment for thermal metal production
US4578031A (en) 1984-11-09 1986-03-25 Midland-Ross Corporation Dimensionally stable movable furnace hearth
US4597564A (en) * 1985-05-23 1986-07-01 The International Metals Reclamation Company, Inc. Rotary hearth
US5186741A (en) * 1991-04-12 1993-02-16 Zia Patent Company Direct reduction process in a rotary hearth furnace
US5885521A (en) * 1994-12-16 1999-03-23 Midrex International B.V. Rotterdam, Zurich Branch Apparatus for rapid reduction of iron oxide in a rotary hearth furnace
US6413471B1 (en) * 1999-09-07 2002-07-02 Mitsubishi Heavy Industries, Ltd. Apparatus for producing reduced iron

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3443931A (en) * 1965-09-10 1969-05-13 Midland Ross Corp Process for making metallized pellets from iron oxide containing material
US4622905A (en) * 1985-03-04 1986-11-18 International Metals Reclamation Co., Inc. Furnacing
US4701214A (en) * 1986-04-30 1987-10-20 Midrex International B.V. Rotterdam Method of producing iron using rotary hearth and apparatus
US5567224A (en) * 1995-06-06 1996-10-22 Armco Inc. Method of reducing metal oxide in a rotary hearth furnace heated by an oxidizing flame
JP3304872B2 (ja) * 1998-03-23 2002-07-22 ミドレックス テクノロジーズ，インコーポレイテッド 回転炉床式加熱炉内における酸化鉄の急速還元方法及び装置

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR803478A (fr) 1936-03-14 1936-10-01 Stewarts & Lloyds Ltd Perfectionnement aux fours à sole tournante
DE1151823B (de) 1960-05-16 1963-07-25 Mannesmann Ag Drehherdofen zum Waermen von Stahlbloecken
US4227875A (en) * 1978-09-12 1980-10-14 Calcimatic International Limited Rotary hearth for calcining kiln
CH649096A5 (en) 1981-11-11 1985-04-30 Technomet Ag Process and equipment for thermal metal production
US4578031A (en) 1984-11-09 1986-03-25 Midland-Ross Corporation Dimensionally stable movable furnace hearth
US4597564A (en) * 1985-05-23 1986-07-01 The International Metals Reclamation Company, Inc. Rotary hearth
US5186741A (en) * 1991-04-12 1993-02-16 Zia Patent Company Direct reduction process in a rotary hearth furnace
US5885521A (en) * 1994-12-16 1999-03-23 Midrex International B.V. Rotterdam, Zurich Branch Apparatus for rapid reduction of iron oxide in a rotary hearth furnace
US6413471B1 (en) * 1999-09-07 2002-07-02 Mitsubishi Heavy Industries, Ltd. Apparatus for producing reduced iron

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
U.S. patent application Ser. No. 09/988,521, Harada et al., filed Nov. 20, 2001.
U.S. patent application Ser. No. 10/395,340, Maki, et al., filed Mar. 25, 2003.
U.S. patent application Ser. No. 10/396,516, Harada et al., filed Mar 26, 2003.

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050087039A1 (en) * 2001-11-12 2005-04-28 Shoichi Kikuchi Method of producing metallic iron
US7384450B2 (en) 2001-11-12 2008-06-10 Kobe Steel, Ltd. Method for producing metallic iron
US20050211020A1 (en) * 2002-10-18 2005-09-29 Hiroshi Sugitatsu Ferronickel and process for producing raw material for ferronickel smelting
US20070113708A1 (en) * 2002-10-18 2007-05-24 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel Ltd.) Ferronickel and process for producing raw material for ferronickel smelting
US20040163493A1 (en) * 2003-02-26 2004-08-26 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Method for manufacturing reduced metal
US7572316B2 (en) 2003-02-26 2009-08-11 Kobe Steel, Ltd. Method for manufacturing reduced metal
US20090136887A1 (en) * 2005-10-11 2009-05-28 Kab. Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Rotary hearth furnace
US7922484B2 (en) * 2005-10-11 2011-04-12 Kobe Steel, Ltd. Rotary hearth furnace

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EP1213362B1 (de) 2006-06-07
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RU2217504C2 (ru) 2003-11-27
AU9710401A (en) 2002-06-13
KR20020045556A (ko) 2002-06-19
TW574373B (en) 2004-02-01
DE60120327D1 (de) 2006-07-20
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CA2364273A1 (en) 2002-06-07
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